This circuit was obtained from Elektor magazine and published in the Encyclopedia of Electronic Circuits Vol 5 of 1995. Transistors are RF types that are still common today.
This circuit is from a Radio Electronics magazine from December 1971. The resistors are power...
This general purpose circuit was found in a Popular Electronics. It is intended for detecting the...
This circuit produces a tone by a small loudspeaker. Frequency depends on C1 and C2. These...